i.e. Might there not be a requirement to pay a nominal fee to enter into a contract-based "license" in some places? Which would seem odd.... :-)
It can take the form of money, physical objects, services, promised actions, abstinence from a future action, and much more. [1]
Sounds like the things GPL (etc) prohibit/promise themselves might count.Here's the problem: If the copyright holder gains nothing in the transaction that the license governs, then the license is not an enforceable contract. Thus, the user cannot enforce the terms of the license against the copyright holder. The copyright holder could, for example, revoke the license at any time and demand everyone stop using the open source software.
I've always wondered: Could an open source license create consideration by referring to the copyright holder's business or career interest in the software enjoying widespread use and acclaim? As a software developer, I could stand to gain financially from the success of my open source project. For example, I could leverage my notoriety into a well-compensated position. Or I could hire myself out as a consultant to users of the open source software. Or I could start a business, and piggyback off the prominence of the open source software to promote my business.
There are also theories whereby promissory estoppel would protect users against copyright holders. I won't comment on these theories except to say that they're pretty much untested.
This area of law is mostly unsettled. There's far too little case law for anyone to make a definitive pronouncement yet.
Why are open source licenses good? Because they make it easier for people to improve their stuff and share those improvements, or write new works based on existing works.
Copyright incentivizes many authors to undertake works they normally might not due to the protections copyright provides. Many authors (who freely publish their books under copyright) probably wouldn't be able to spend 3 years researching and writing a book if they weren't able to get advance money from their publisher.
One is free to use a liberal license or a more restrictive license, both are out there and available to creators.